Vibrio cholerae
MiF #2
Clinical Features :
Sudden onset painless watery diarrhea, muscle cramps, no fever.
Complications – hypovolemic shock, renal failure, pulmonary edema, paralytic ileus. It causes a notifiable disease.
Virulence Factors :
Potent phage mediated enterotoxin (resembles LT toxin of E.coli) with units A1, A2 and B. It is ADP-ribosyl transferase, increase levels of cAMP & increase secretion of electrolytes.
Culture & Gram Reaction :
Specimen- stool before antibiotic administration, rectal swab; vomitus not useful.
Transport at 4C in VR fluid or Cary-Blair medium
Plating media : Alkaline bile salt agar, Monsur’s GTTA medium, TCBS medium. NaCl (0.5-1%) for optimum growth
Shows string test and darting motility.
Gram Negative short curved rod with round ends, non acid-fast, stain readily with aniline dyes.
Classified by Heiberg grouping; Gardener & Venkataraman classification
Biochemicals :
Catalase +
Oxidase +
Indole +
Nitrate reduced to nitrite
MR, Urease negative
fermentation produce acid but no gas
Treatment
ORS; Antibiotic therapy of secondary importance